OMCVD on Fluidized Divided Substrates : a Potential Method for the Preparation of Catalysts

The OMCVD method has been used to deposit highly pure metal particles on porous divided substrates in order to prepare metal supported catalysts. A fluidized bed reactor has been especially designed and the requirements of CVD and fluidization have been taken into account to select convenient experimental conditions. Three organometallic compounds of rhodium have been selected and their thermal decomposition under He and He/H2 mixtures studied by infrared spectroscopy and on-line mass spectrometry analyses. The deposition are carried out at a total pressure of 100 Torr and substrate temperatures as low as 100°C. The solid deposits have been characterized by XPS, the size and dispersion of the particules have been determined by chemisorption methods or measured by TEM. These catalysts can be used without further treatment and their performances have been compared to those of conventionally prepared ones.